The key events during his reign were the contest with the Ottoman Empire, whose great advance into Central Europe began in the 1520s, and the Protestant Reformation, which resulted in several wars of religion. Ferdinand was able to defend his realm and make it somewhat more cohesive, but he could not conquer the major part of Hungary. His flexible approach to Imperial problems, mainly religious, finally brought more result than the more confrontational attitude of his brother.

Ferdinand's motto was : "Let justice be done, though the world perish".